This invention relates to hand tools, and in particular the invention is concerned with a hand tool for projecting two or more reference beams of visible light for precise alignment on floors.
For some time laser beams have been used in construction for level reference, vertical references and layout on floors. The subject invention pertains to the last application, floor layout. It allows the user to project visible lines on the floor at precise angles for the purpose of marking the floor or to direct positions of objects or installations on the floor. Typically a construction worker marks the floor indicating the location of walls or other building elements to be constructed. In a like manner a tile layer marks the floor with reference lines. This is often done using a tape measure and a 3-4-5 triangle as shown in FIG. 1 of the drawings. This method is inaccurate and often requires two men. In an alternate method a transit equipped with a calibrated turntable is often used as shown in FIG. 2. In this case the operator sets the tripod over the first point with the aid of a plumb bob. Then the telescope of the transit is used to sight a known second point and the turntable angle is noted. Subsequently the turntable is turned to the required angle and the needed third point is marked by a second person communicating with the transit operator. This method can be very accurate but requires two men and is time consuming.
Many existing methods use small battery operated lasers to aid in the job of construction layout. For example, laying out 90.degree. reference lines can be done using a visible laser beam generator such as the LeveLite manufactured by the assignee of this application. With that tool on its side, the self-leveling feature of the tool is disabled and visible light beams at 90.degree. to each other can be used to project two lines at 90.degree. to each other. FIG. 3 shows such a LeveLite tool 2 on an adjustable trivet 8. The light beams 4 and 6 may be pointed on a target or on the floor using knobs 10. The floor is subsequently marked for later use. In this case the lines are relatively short and difficult to position. To make the line on the floor longer a cylinder lens may be used as is shown in FIG. 4 depicting a system of U.S. Pat. No. 5,864,956. In this case a number of individual units project individual fan beams, with the beams fixed in their orientation to each base. The operator is unable to move the fan beam to position it on the floor where it is needed. Because the blocks are fastened together, tipping one axis to move the fan beam up or down causes the fan beam at 90.degree. to rotate causing it to be no longer vertical.
In U.S. Pat. No. 5,539,990, as shown in FIG. 5, a self-leveling platform with two fan beams at 90.degree. to each other is used. It uses a weight 11 and a bearing not shown to level the platform 13. In this case the beam location is not controlled by the operator and, therefore, a wide beam must be used spreading the light over a wide angle making it difficult to see.
Rotating lasers with a special transmitting penta prism are often used in this application, as shown in FIG. 6. In this case the rotating laser beam is visible on the floor or may be detected using a handheld detector. A portion of the beam is transmitted through the penta prism providing a 90.degree. reference. This technique is expensive and it is difficult to see the beam because the light is spread over 360.degree..
An instrument using two rotating lasers is described in U.S. Pat. No. 5,218,770 and shown in FIG. 7. Again, the laser beams from this unit are difficult to see because the light is spread over a large area. In U.S. Pat. No. 5,218,770 two planes of light at 90.degree. to each other are generated using a mirrored cone and two mirrors. The beams are so weak in this case that a special detector must be used to find the beam and in addition, two men may be required.
The subject invention is designed to overcome the limitations of the prior art by making the light-generated reference lines more visible and also adjustable as to height of projection, allowing layout by a single operator.